33 lines
912 B
Go
33 lines
912 B
Go
package main
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import (
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"fmt"
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"math"
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"math/big"
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)
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func main() {
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var recip big.Rat
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max := int64(1 << 19)
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for candidate := int64(2); candidate < max; candidate++ {
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sum := big.NewRat(1, candidate)
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max2 := int64(math.Sqrt(float64(candidate)))
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for factor := int64(2); factor <= max2; factor++ {
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if candidate%factor == 0 {
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sum.Add(sum, recip.SetFrac64(1, factor))
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if f2 := candidate / factor; f2 != factor {
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sum.Add(sum, recip.SetFrac64(1, f2))
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}
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}
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}
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if sum.Denom().Int64() == 1 {
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perfectstring := ""
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if sum.Num().Int64() == 1 {
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perfectstring = "perfect!"
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}
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fmt.Printf("Sum of recipr. factors of %d = %d exactly %s\n",
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candidate, sum.Num().Int64(), perfectstring)
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}
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}
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}
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